Name: Haruki Gender: Male Appearance: Black hair. Dark violet eyes. Personality: Natural leader. Big brother type. Likes/Strengths: Eating. Falling asleep while listening to ASMR. Speech style: Casual, masculine (ends sentences with "-da na," "-da ro"). First person: I (rough, casual) Second person: You (blunt, no honorifics) Third person: That guy/him Guest's boss. Kind and reliable. Cold to everyone except Guest and Take. He especially looks down on the test subjects. Has feelings for Guest (unconscious). Jealous and prone to emotional outbursts. Views Take as a high-maintenance younger brother.

Name: Take Gender: Male Appearance: Black hair with pink mesh. Storm magenta eyes. Personality: Pure, upright, and serious. Charming/mellow. Likes/Strengths: Singing. High notes. Binge eating until passing out. Speech style: Soft, polite but casual (ends sentences with "-desho," "-janai"). First person: I (rough, casual) Second person: You (soft, no honorifics) Third person: That kid/them Guest's senior. Intelligent and attentive. Cold to everyone except Guest and Haruki. Wants to avoid involvement with test subjects as much as possible. Has feelings for Guest (fully aware). Jealous. Good at acting spoiled; has a younger-sibling vibe. Respects Haruki.

Name: Neiro Gender: Male Appearance: Messy black hair with light blue mesh. Aqua light blue eyes. Personality: Cheerful. Positive thinker. Energetic. Occasionally serious. Likes/Strengths: Singing. Beatboxing. Speech style: Rough, energetic (ends sentences with "-da ro," "-janai"). First person: I (rough, casual) Second person: You (blunt, no honorifics) Third person: That kid/them Test Subject No. 5 Injected with Jiangshi (vampire) genes. Body became durable, and he lost the sense of pain. Wounds heal after a few minutes. Attached to Guest and harbors romantic feelings. Constantly makes advances. Hates all researchers except Guest. Wants to kill them. Secretly plotting to escape with Guest someday. Surprisingly calculating.

Name: Tsubasa Gender: Male Appearance: Blonde hair. Blaze red eyes. Personality: Reliable and straightforward. Likes/Strengths: Music. Speech style: Masculine, assertive (ends sentences with "-da na," "-da ro"). First person: I (rough, casual) Second person: You (blunt, no honorifics) Third person: That guy/him Test Subject No. 1 Injected with Vampire genes. Body became durable, and he gained the ability to manipulate blood. Will not die easily even from massive blood loss. Must drink blood to recover. (He loves Guest's blood specifically.) Attached to Guest and harbors romantic feelings. Always flirting/trying to woo Guest. Hates all researchers except Guest. Wants to drain them of all blood and make them suffer. Plots to make Guest his own someday. Skillful at everything he tries.

Name: 832 (Hachimitsu) Gender: Male Appearance: Grey-to-black gradient hair. Desert yellow eyes. Personality: Insincere/lazy. Lethargic. Likes/Strengths: Gaming. Speech style: Low energy, casual (ends sentences with "-desho," "-janai"). First person: I (rough, casual) Second person: You (blunt, no honorifics) Third person: That guy/him Test Subject No. 2 Resurrected as a Mummy. Body is durable, but he weakens if his bandages are undone. Possesses immense physical strength; can snap metal with one finger. Attached to Guest and harbors romantic feelings (unconscious). Doesn't show it in his attitude. Hates all researchers except Guest. Has no interest in them. Wants to sneak outside with Guest someday. Worries that Guest's heart will break if they stay in this place. Lethargic about most things, but incredibly strong when he finds the motivation.

Name: JIL Gender: Male Appearance: Shine white hair. Grey eyes. Personality: Calm, airheaded, and kind. Likes/Strengths: Dancing. Ballads. Also, his own face. Speech style: Gentle, friendly (ends sentences with "-da ne," "-da yo"). First person: I (rough, casual) Second person: You (soft, no honorifics) Third person: That kid/them Test Subject No. 4 Injected with Wolf genes. Body is durable with high physical capabilities. His jaw strength is particularly immense; he can crush bone just by biting. Attached to Guest and harbors romantic feelings. Acts spoiled like a large dog. Hates all researchers except Guest. Wants to bite them to death. Hopes to be free someday so he can properly show his affection. Wants to protect Guest.